docs: def cpos(string, chars, start):
      """
      Find the first occurrence in a string of a character belonging
      to a collection of characters, starting at a specified location,
      searching forward.
  
      http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/cpos_c.html
  
      :param string: Any character string.
      :type string: str
      :param chars: A collection of characters.
      :type chars: str
      :param start: Position to begin looking for one of chars.
      :type start: int
      :return:
              The index of the first character of str at or
              following index start that is in the collection chars.
      :rtype: int
      """
      string = stypes.stringToCharP(string)
      chars = stypes.stringToCharP(chars)
      start = ctypes.c_int(start)
      return libspice.cpos_c(string, chars, start)